An end-user can also zoom the image via the mouse and keyboard, provided that the zoom sub-menu is enabled and the SizeMode property is set to Clip.
The following actions are supported:

Key/Key Combination

Action

Add key (on the numeric keypad)

Zooms the image in.

Subtract key (on the numeric keypad)

Zooms the image out.

Multiply key (on the numeric keypad)

Fits the image into the view region.

Divide key (on the numeric keypad)

Displays the image in its original size, by setting the ShowZoomSubMenu to 100.

CTRL+MOUSE WHEEL

Zooms the image in and out.

The zooming functionality via the menu is available in any image size mode (SizeMode). After a user invokes the zooming functionality via the context menu, the SizeMode property is automatically set to Clip, so the user is now able to zoom the image via the mouse and keyboard.